Project Summary Primary central nervous system lymphoma (PCNSL) is an extranodal variant of non-Hodgkin lymphoma (NHL) that is confined to the nervous system. The diagnostic and therapeutic approaches to PCNSL are different from those that are applied to other forms of NHL or to other brain cancers. The International Primary Central Nervous System Lymphoma Collaborative Group (IPCG) consists of specialists from multiple countries and disciplines dedicated to the study of PCNSL. The IPCG holds an annual scientific conference at the American Society of Hematology meeting in which various research topics related to PCNSL are discussed. An international expert on the topic under discussion is selected each year by an executive committee to chair the scientific conference. These meetings have led to multiple collaborative projects that have positively impacted the field and that have been published in the peer- reviewed literature. The annual IPCG meeting is a critical forum for generating new ideas and approaches to this unique form of brain cancer and lymphoma. The 2017 conference topic is Novel imaging techniques in PCNSL. Serial imaging by standard magnetic resonance imaging (MRI) techniques is the ?gold standard? of assessing response in the PCNSL patient population and has been incorporated into the consensus criteria developed by the IPCG for assessment of response in PCNSL patients (Abrey et al, 2005). However, the optimal role of novel MRI techniques (diffusion weighted images, perfusion images and spectroscopy) have not been defined. For example, there is preliminary data suggesting that early application of diffusion weighted MRI techniques may allow early prediction of response in the PCNSL patient population (Barajas et al, 2010). Moreover, the role(s) of brain FDG-PET imaging or the use of novel radiotracers is largely unexplored. The 2017 symposium is planned to assess the current and future role that imaging will play in the assessment of disease and neurotoxicity status in PCNSL. A conference focused on this problem is of high priority for the IPCG.